On the Mechanism of Interaction between Strong Earthquakes and Volcanism in Subduction Zones

Abstract

The relationship between strong earthquakes and powerful volcanism in subduction zones are discussed. It is shown that abnormally strong earthquakes or a group of strong earthquakes and powerful volcanic events or volcanic activation of large areas can be considered as an interconnected geodynamic pair. At high level of horizontal compression, magma-conducting faults are clamped and volcanism in the upper part of the crust is hindered. Mega-earthquakes or a series of strong earthquakes reduce the level of the horizontal compression in the crust of the island arc (continent active margin), which creates favorable conditions for the resumption of volcanic activity. For major faults, located along the strike of subduction zones, upward movement of magma during volcanic eruptions or intracrustal magmatism leads to an increase in the stresses of horizontal compression in the surrounding rocks up to the pressure level of rising magma. As a result, the stress state of horizontal compression is restored in the crust and, thus, the cycle is closed. The state in which earthquakes are an effective mechanism for reducing stresses occurs once again.